In data processing systems, disc drives are often used as storage devices. Such drives use rigid discs, which are coated with a magnetizable medium for storage of digital information in a plurality of circular, concentric data tracks. The discs are mounted on a spindle motor, which causes the discs to spin and the surfaces of the discs to pass under respective hydrodynamic (e.g. air) bearing disc head sliders. The sliders carry transducers, which write information to and read information from the disc surfaces.
An actuator mechanism moves the sliders from track-to-track across the surfaces of the discs under control of electronic circuitry. The actuator mechanism includes a track accessing arm and a suspension for each slider assembly. The suspension includes a load beam and a gimbal. The load beam provides a load force which forces the slider toward the disc surface. The gimbal is positioned between the slider and the load beam, or is integrated in the load beam, to provide a resilient connection that allows the slider to pitch and roll while following the topography of the disc.
The slider includes a bearing surface, which faces the disc surface. As the disc rotates, the disc drags air under the slider and along the bearing surface in a direction approximately parallel to the tangential velocity of the disc. As the air passes beneath the bearing surface, air compression along the air flow path causes the air pressure between the disc and the bearing surface to increase, which creates a hydrodynamic lifting force that counteracts the load force and causes the slider to lift and fly above or in close proximity to the disc surface.
One type of slider is a “self-loading” air bearing slider, which includes a leading taper (or stepped-taper), a pair of raised side rails, a cavity dam and a sub-ambient pressure cavity. The leading taper is typically lapped or etched onto the end of the slider that is opposite to the recording head. The leading taper pressurizes the air as the air is dragged under the slider by the disc surface. An additional effect of the leading taper is that the pressure distribution under the slider has a first peak near the taper end or “leading edge” due to a high compression angle of the taper or step, and a second peak near the recording end or “trailing edge” due to a low bearing clearance for efficient magnetic recording. This dual-peak pressure distribution results in a bearing with a relatively high pitch stiffness.
The bearing clearance between the slider and the disc surface at the recording height is an important parameter to disc drive performance. Efforts have been made to design sliders having specialized features on the disc-facing surface that enable the slider to operate at particularly low fly heights. As slider designs evolve and average flying heights continue to be reduced, contamination particles have been observed to become an increasing source of head modulation leading, in some cases, to read/write failures. Many low fly height slider designs have been observed to disadvantageously encourage an accumulation of contamination particles near the trailing edge bearing surface of the slider and/or the transducer region of the slider. Particles that reach these regions of the slider can occasionally lead to irrecoverable data loss.
Many slider designs include a center pad bearing surface (e.g., an air bearing surface) that is situated proximate a trailing edge of the slider's disc-facing surface. The center pad bearing surface is typically situated proximate the transducer and centered laterally along the trailing edge. In many instances, the slider's other disc-facing surface features are configured such that the flow (e.g., air flow) directed at the center pad bearing surface during operation is not emphasized. Configurations such as these are disadvantageous in that it has been observed that an increased pressurization of the center pad bearing surface improves the disc following capability of the transducer.
Embodiments of the present invention provide solutions to these and other problems, and offer advantages over the prior art.